18650 battery bank free charge protection module

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I am showing here, how can you find a charge protection module for 18650 battery bank for free. Make battery bank for mobile charging or use it for led emergency light. The lithium cells are most common and easily available in local market. Also you can remove them from any scrap or damaged laptop battery packs.

Development images

of 18650 battery bank free

Removing the charge protection board:

Take any damaged 3.7 volts mobile battery. Remove its upper cover very carefully from the top where the power connections are visible. Use all safety precautions like hand gloves, goggles etc. Do it in open area outside the room or house. Don’t hit or cut the battery itself, only remove the top gently. And also do not touch both the connection simultaneously which can cause shortage circuit if the battery is charged.

18650 Battery Bank Free Image1

Assembling the battery bank:

Arrange 3 pieces of 18650 lithium batteries. You can easily find and remove from any laptop battery pack. Check its gravity voltage with multi tester. If it shows more than 3 volts then it can be used for this project. Don’t use the dead cells. Also arrange 6 pieces of jackets/cell holders which is optional and fix them as shown in the following image. All cells should be in parallel. If you don’t have cell holding jacket, you can simply use any paper or electrical tape and wrap around nicely. Keep all positive terminals of the cells in one side and the negative terminals on the other side.

18650 Battery Bank Free Image2

Solder all positive terminals of 3 cells with piece of thick naked wire together and also solder all negative sides together as shown. Likewise all the cells will be joined in parallel. The voltage will remain the same as one cell was having i.e. 3.7 volts. But the amperes will be triple. This single cell contains 2200 mAh which will be 6600 mAh after joining all three cells in parallel but the voltage will remain 3.7v.

18650 Battery Bank Free Image3

External connections:

Now take the charge protection board which was removed from the damaged mobile battery. Connect its negative out of protection board to negative side of cells. And positive out of protection board to positive side of cells. Now take 2 piece of wires red & black and connect them to positive & negative-in of the protection board for recharging the cells.

18650 Battery Bank Free Image4

Now take a power female socket and attach the 2 wires coming from the protection board to plus & minus side of power socket. Your battery bank is ready to charge with any 5 volts mobile charger.


Test the voltage before charging and keep supply on for charging. The protection board will stop charging automatically after full charge of batteries. Test it and use it. Solder two more wire directly in plus & minus sides of the cells for use externally which is not shown in the following image. Connect those two wires with the device you want to run with 3.7 volts 6600 mAh. Like this way you can make your own battery bank at home with very little efforts. I hope you enjoyed the project


List of components

  • 18650 lithium battery cell x 3
  • Cell holder jackets x 6
  • Charge protection module x 1
  • Power socket x 1
  • Connection wires

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